Lighting device for use in an optical scanning unit, of an image reader

ABSTRACT

In a lighting device, a light source emits light. A second sandwiching member includes a second opposed surface opposing a first opposed surface of a first sandwiching member. The first sandwiching member and the second sandwiching member sandwich the light source in such a manner that the light source is detachably attached to the first sandwiching member and the second sandwiching member. A reflection member is provided on the first opposed surface of the first sandwiching member and the second opposed surface of the second sandwiching member to reflect the light emitted by the light source toward an irradiation region on an original document sheet. A positioning member is provided in the first opposed surface of the first sandwiching member and the second opposed surface of the second sandwiching member to position the light source with respect to the reflection member.

PRIORITY STATEMENT

The present patent application claims priority from Japanese PatentApplication No. 2008-162025, filed on Jun. 20, 2008, in the Japan PatentOffice, the entire contents of which are hereby incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Example embodiments generally relate to a lighting device, an opticalscanning unit, an image reader, and an image forming apparatus, and moreparticularly, to a lighting device for irradiating an original documentsheet, an optical scanning unit, an image reader, and an image formingapparatus including the lighting device, for example.

2. Description of the Related Art

Related-art image forming apparatuses, such as copiers, facsimilemachines, image scanners, or multifunction printers having at least oneof copying, printing, scanning, and facsimile functions, typically forman image on a recording medium (e.g., a sheet) according to image datausing electrophotography. Thus, for example, an image reader reads animage on an original document sheet to generate image data; a chargeruniformly charges a surface of an image carrier; an optical writer emitsa light beam onto the charged surface of the image carrier to form anelectrostatic latent image on the image carrier according to the imagedata; a development device supplies toner particles to the electrostaticlatent image formed on the image carrier to make the electrostaticlatent image visible as a toner image; the toner image is directlytransferred from the image carrier onto a sheet or is indirectlytransferred from the image carrier onto a sheet via an intermediatetransfer member; a cleaner then cleans the surface of the image carrierafter the toner image is transferred from the image carrier onto thesheet; finally, a fixing device applies heat and pressure to the sheetbearing the toner image to fix the toner image on the sheet, thusforming the image on the sheet.

In such image forming apparatuses, the image reader may include alighting device in which a light-emitting diode (LED) is used as a lightsource to provide quick warm-up, energy saving, and a long life of thelight source.

However, the LED has a small light-emitting surface, roughly equivalentto a point source, and therefore does not provide uniform illuminancedistribution in a sub-scanning direction. To address this problem,related-art lighting devices may include a guide member to guide lightemitted by the LED.

Thus, for example, a related-art image reader may include a lightingdevice including a plurality of point sources, a guide member formed oftransparent resin or glass, and a positioning member. The plurality ofpoint sources is aligned so as to irradiate an original document sheetthrough an exposure glass, with the guide member guiding light emittedby the plurality of point sources to irradiate the original documentsheet in a main scanning direction. The positioning member positions theplurality of point sources with respect to the guide member in such amanner that a constant gap is provided between the plurality of pointsources and the guide member, and a direction in which the plurality ofpoint sources is aligned corresponds to a longitudinal direction of theguide member.

However, some original documents present special problems. Thus, forexample, when an open book or a thick sheet is placed on the exposureglass, a center portion of the open book lifted from the exposure glass,or a step formed between the thick sheet and the exposure glass, mayresult in a shaded image of the original.

To address this problem, some image readers include first and secondlighting devices which include first and second light sources and firstand second guide members for guiding light emitted by the first andsecond light sources to an original document sheet, respectively. Thefirst lighting device is provided upstream from an irradiation region inwhich light emitted by the first light source irradiates the originaldocument sheet in the sub-scanning direction, and the second lightingdevice is provided downstream from the irradiation region in thesub-scanning direction.

However, although such an arrangement can solve the problem describedabove, in such an image reader, the light sources need to be positionedprecisely with respect to the guide members to obtain proper illuminancedistribution, thus complicating maintenance of the image reader.

SUMMARY

At least one embodiment may provide a lighting device that includes alight source, a first sandwiching member, a second sandwiching member, areflection member, and a positioning member. The light source emitslight. The first sandwiching member includes a first opposed surface.The second sandwiching member includes a second opposed surface opposingthe first opposed surface of the first sandwiching member. The firstsandwiching member and the second sandwiching member sandwich the lightsource in such a manner that the light source is detachably attached tothe first sandwiching member and the second sandwiching member. Thereflection member is provided on the first opposed surface of the firstsandwiching member and the second opposed surface of the secondsandwiching member to reflect the light emitted by the light sourcetoward an irradiation region on an original document sheet. Thepositioning member is provided in the first opposed surface of the firstsandwiching member and the second opposed surface of the secondsandwiching member to position the light source with respect to thereflection member.

At least one embodiment may provide a lighting device that includes alight source, a first sandwiching member, a second sandwiching member, areflection member, and a concave member. The light source emits light,and includes a board mounting a plurality of light emitting elementsaligned substantially straight in a main scanning direction. The firstsandwiching member includes a first opposed surface. The secondsandwiching member includes a second opposed surface opposing the firstopposed surface of the first sandwiching member. The first sandwichingmember and the second sandwiching member sandwich the board of the lightsource in such a manner that the light source is detachably attached tothe first sandwiching member and the second sandwiching member. Thereflection member is provided on the first opposed surface of the firstsandwiching member and the second opposed surface of the secondsandwiching member to reflect the light emitted by the light sourcetoward an irradiation region on an original document sheet. The concavemember is provided in the first opposed surface of the first sandwichingmember and the second opposed surface of the second sandwiching memberto engage the board of the light source.

At least one embodiment may provide a lighting device that includesmeans for emitting light, first and second means for sandwiching themeans for emitting, means for reflecting the light emitted by the meansfor emitting, and means for positioning the means for emitting withrespect to the means for reflecting.

The first means for sandwiching the means for emitting includes a firstopposed surface. The second means for sandwiching the means for emittingincludes a second opposed surface opposing the first opposed surface ofthe first means for sandwiching the means for emitting. The means foremitting is detachably attached to the first and second means forsandwiching the means for emitting. The means for reflecting the lightemitted by the means for emitting toward an irradiation region on anoriginal document sheet is provided on the first opposed surface of thefirst means for sandwiching and the second opposed surface of the secondmeans for sandwiching. The means for positioning the means for emittingwith respect to the means for reflecting is provided in the firstopposed surface of the first means for sandwiching and the secondopposed surface of the second means for sandwiching.

Additional features and advantages of example embodiments will be morefully apparent from the following detailed description, the accompanyingdrawings, and the associated claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of example embodiments and the manyattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

FIG. 1 is a schematic view of an image forming apparatus according to anexample embodiment;

FIG. 2 is a schematic perspective view (according to an exampleembodiment) of an image reader included in the image forming apparatusshown in FIG. 1;

FIG. 3 is a sectional view (according to an example embodiment) of anoptical scanning unit included in the image reader shown in FIG. 2;

FIG. 4 is a perspective view (according to an example embodiment) of anLED (light-emitting diode) unit included in the optical scanning unitshown in FIG. 3;

FIG. 5 is a sectional view (according to an example embodiment) of acover included in the optical scanning unit shown in FIG. 3;

FIG. 6 is a perspective bottom view (according to an example embodiment)of the cover shown in FIG. 5;

FIG. 7 is a sectional view (according to an example embodiment) of ashield member included in the optical scanning unit shown in FIG. 3;

FIG. 8 is a perspective top view (according to an example embodiment) ofthe shield member shown in FIG. 7;

FIG. 9 is a perspective top view (according to an example embodiment) ofthe cover shown in FIG. 5;

FIG. 10 is a perspective top view (according to an example embodiment)of a housing included in the optical scanning unit shown in FIG. 3;

FIG. 11 is an exploded, partially perspective view (according to anexample embodiment) of the optical scanning unit shown in FIG. 3 whenthe housing shown in FIG. 10, the shield member shown in FIG. 7, and thecover shown in FIG. 5 are disassembled from each other;

FIG. 12 is an exploded, partially perspective view (according to anexample embodiment) of the optical scanning unit shown in FIG. 3 whenthe housing shown in FIG. 10 and the shield member shown in FIG. 7 aredisassembled from the cover shown in FIG. 5;

FIG. 13 is a partially perspective view (according to an exampleembodiment) of the optical scanning unit shown in FIG. 3 when thehousing shown in FIG. 10, the shield member shown in FIG. 7, and thecover shown in FIG. 5 are assembled;

FIG. 14 is a perspective top view of a cover according to anotherexample embodiment;

FIG. 15 is a partially perspective view (according to an exampleembodiment) of an optical scanning unit including the cover shown inFIG. 14; and

FIG. 16 is a schematic view of an image forming apparatus according toyet another example embodiment.

The accompanying drawings are intended to depict example embodiments andshould not be interpreted to limit the scope thereof. The accompanyingdrawings are not to be considered as drawn to scale unless explicitlynoted.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

It will be understood that if an element or layer is referred to asbeing “on”, “against”, “connected to”, or “coupled to” another elementor layer, then it can be directly on, against, connected or coupled tothe other element or layer, or intervening elements or layers may bepresent. In contrast, if an element is referred to as being “directlyon”, “directly connected to”, or “directly coupled to” another elementor layer, then there are no intervening elements or layers present. Likenumbers refer to like elements throughout. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper”, and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, term such as “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein are interpreted accordingly.

Although the terms first, second, etc. may be used herein to describevarious elements, components, regions, layers and/or sections, it shouldbe understood that these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are used onlyto distinguish one element, component, region, layer, or section fromanother region, layer, or section. Thus, a first element, component,region, layer, or section discussed below could be termed a secondelement, component, region, layer, or section without departing from theteachings of the present invention.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the presentinvention. As used herein, the singular forms a “an”, and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“includes” and/or “including”, when used in this specification, specifythe presence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

In describing example embodiments illustrated in the drawings, specificterminology is employed for the sake of clarity. However, the disclosureof this specification is not intended to be limited to the specificterminology so selected and it is to be understood that each specificelement includes all technical equivalents that operate in a similarmanner.

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views,particularly to FIG. 1, an image forming apparatus 1 according to anexample embodiment is explained.

As illustrated in FIG. 1, the image forming apparatus 1 includes an autodocument feeder (ADF) 2, a sheet supplier 3, an image reader 4, and/oran image forming device 5.

The ADF 2 includes an original tray 11, a sheet feeder 13, a conveyancebelt 8, a sheet discharger 9, and/or a discharge tray 12.

The sheet supplier 3 includes paper trays 21 and 22 and/or a sheetfeeder 23.

The image reader 4 includes an exposure glass 7, an optical scanningunit 40, a housing 4A, and/or a driver 40A.

The image forming device 5 includes an exposure device 31,photoconductive drums 32, development devices 33, a transfer belt 34,and/or a fixing device 35.

The image forming apparatus 1 can be a copier or a facsimile machineincluding an image scanner, a multifunction printer having at least oneof copying, printing, scanning, plotter, and facsimile functions, or thelike. According to this example embodiment of the present invention, theimage forming apparatus 1 functions as a color copier for forming acolor image on a recording medium by electrophotography.

In the ADF 2, the sheet feeder 13 includes rollers for feeding originaldocument sheets placed on the original tray 11 one by one toward theexposure glass 7 of the image reader 4. For example, the sheet feeder 13separates an original document sheet from other original document sheetsplaced on the original tray 11, and feeds the separated originaldocument sheet toward the exposure glass 7.

The conveyance belt 8 conveys the original document sheet fed by thesheet feeder 13 on the exposure glass 7. After the image reader 4 readsan image on the original document sheet placed on the exposure glass 7,the conveyance belt 8 discharges the original document sheet out of theexposure glass 7 toward the sheet discharger 9. The sheet discharger 9includes rollers for feeding the original document sheet toward thedischarge tray 12 provided under the original tray 11. The ADF 2 isopened and closed with respect to the image reader 4 via an open-closemechanism including a hinge.

In the sheet supplier 3, the paper trays 21 and 22 load sheets ofdifferent sizes, serving as a recording medium, respectively. The sheetfeeder 23 includes rollers for feeding a sheet from the paper tray 21 or22 toward the image forming device 5.

The image reader 4 may be an image scanner. In the image reader 4, theoptical scanning unit 40, which is an all-in-one unit, is providedinside the housing 4A of the image reader 4. The driver 40A provided inthe image reader 4 moves the optical scanning unit 40 in a direction B,that is, a sub-scanning direction. The exposure glass 7 is disposed onthe housing 4A of the image reader 4 to serve as a top surface of thehousing 4A.

The driver 40A for moving the optical scanning unit 40 may be a knowndriver including a wire, a plurality of pulleys including a drivingpulley and a driven pulley, and/or a motor. For example, the wire isfixed to the optical scanning unit 40. The plurality of pulleys is laidover the wire. The motor rotates the driving pulley.

In the image forming device 5, the exposure device 31 formselectrostatic latent images on the photoconductive drums 32 rotatingcounterclockwise in FIG. 1 according to image data corresponding torespective colors (e.g., cyan, yellow, magenta, and black) and sent fromthe image reader 4. The development devices 33 oppose thephotoconductive drums 32 and contain cyan, yellow, magenta, and blacktoners, respectively. The development devices 33 supply the cyan,yellow, magenta, and black toners to the electrostatic latent imagesformed on the photoconductive drums 32 to make the electrostatic latentimages visible as cyan, yellow, magenta, and black toner images,respectively.

The cyan, yellow, magenta, and black toner images formed on thephotoconductive drums 32, respectively, are transferred and superimposedonto the transfer belt 34 rotating clockwise in FIG. 1 to form a colortoner image on the transfer belt 34. The color toner image formed on thetransfer belt 34 is transferred onto a sheet sent from the sheetsupplier 3. Thereafter, the fixing device 35 melts toners forming thecolor toner image to fix the color toner image on the sheet.

The image forming apparatus 1 may include an image transmitter-receiverfor sending image data generated by reading an image on an originaldocument sheet to a destination device (e.g., an external device).

FIG. 2 is a schematic perspective view of the image reader 4. In theoptical scanning unit 40 of the image reader 4, an LED (light-emittingdiode) unit (described below) emits light in a direction A, that is, amain scanning direction. The driver 40A (depicted in FIG. 1) provided inthe image reader 4 moves the optical scanning unit 40 in the directionB, that is, the sub-scanning direction, throughout a whole irradiationregion W, so that the image reader 4 reads a two-dimensional image on anoriginal document sheet.

Referring to FIGS. 3 to 13, the following describes a structure of theoptical scanning unit 40. FIG. 3 is a sectional view of the opticalscanning unit 40. The optical scanning unit 40 includes a housing 41, areading device 54, a lighting device 56, a first space 57, and/or asecond space 58.

The reading device 54 includes reflection mirrors 60A, 60B, 60C, 60D,and 60E, an image forming lens 61, a CCD (charge coupled device) 63,and/or an SBU (scanner board unit) 64.

The lighting device 56 includes a shield member 42, a cover 43, anopening 43A, an LED (light-emitting diode) unit 44, reflection members47 to 49, and/or grooves 50 and 51.

The shield member 42 includes an opposed surface 42A and/or a slit 59.

The cover 43 includes an opposed surface 43B.

The LED unit 44 includes an LED board 45 and/or an LED package 46.

The shield member 42, serving as a second sandwiching member, isdetachably attached to the housing 41. The cover 43, serving as a firstsandwiching member, is detachably attached to the shield member 42. TheLED unit 44 emits light to an irradiation region W1 on an originaldocument sheet P through the opening 43A provided between the shieldmember 42 and the cover 43. Each of the housing 41, the shield member42, and the cover 43 includes resin.

The LED unit 44, serving as a light source, is attached to the shieldmember 42 and the cover 43. FIG. 4 is a perspective view of the LED unit44. As illustrated in FIG. 4, in the LED unit 44, a plurality of LEDpackages 46, serving as a plurality of light emitting elements, isaligned on the LED board 45, serving as a board, substantially straightin the direction A, that is, the main scanning direction. According tothis example embodiment, seven LED packages 46 are provided on the LEDboard 45.

According to this example embodiment, a top view type LED package isused as the LED package 46. For example, the LED package 46 emits lightfrom an emission surface in a direction perpendicular to a packagingsurface mounted on the LED board 45.

The top view type LED package 46 has directivity in emission intensitydistribution. Emission light has intensity distribution corresponding toLambert's law of cosines, so-called Lambert's distribution based on aluminous surface perpendicular to an emission angle. FIG. 3 is asectional view of the optical scanning unit 40, which illustrates one ofthe LED packages 46.

As illustrated in FIG. 3, the reflection member 47 is provided on alower surface of the cover 43. The reflection members 48 and 49 areprovided on an upper surface of the shield member 42, which opposes thecover 43.

For example, the reflection member 47 is provided on the opposed surface43B serving as the lower surface of the cover 43 and a first opposedsurface. The reflection members 48 and 49 are provided on the opposedsurface 42A serving as the upper surface of the shield member 42 and asecond opposed surface, which opposes the opposed surface 43B of thecover 43.

The LED board 45 is provided between the shield member 42 and the cover43 in a direction in which a center axis of emission light emitted bythe LED package 46 is substantially parallel to a horizontal direction.An upper end of the LED board 45 engages the groove 50 serving as apositioning member or a concave member provided in the opposed surface43B of the cover 43. A lower end of the LED board 45 engages the groove51 serving as a positioning member or a concave member provided in theopposed surface 42A of the shield member 42. Thus, the LED board 45 andthe grooves 50 and 51 uniquely determine a position of the LED package46.

When the LED board 45 engages the grooves 50 and 51, the LED unit 44 issandwiched between the shield member 42 and the cover 43. When the LEDboard 45 disengages the grooves 50 and 51, the LED unit 44 is separatedfrom the shield member 42 and the cover 43. In other words, the LED unit44 is detachably attached to the shield member 42 and the cover 43.

FIG. 5 is a sectional view of the cover 43. FIG. 6 is a perspectivebottom view of the cover 43. As illustrated in FIG. 6, the cover 43further includes holes 53A and 53B.

FIG. 7 is a sectional view of the shield member 42. As illustrated inFIG. 7, the shield member 42 further includes a protrusion 52B.

FIG. 8 is a perspective top view of the shield member 42. As illustratedin FIG. 8, the shield member 42 further includes protrusions 52A and 67and/or a bolt hole 72.

FIG. 9 is a perspective top view of the cover 43.

As illustrated in FIG. 8, the protrusions 52A and 52B are provided atboth ends of the shield member 42 in the direction A, that is, the mainscanning direction, and protrude upward from the both ends of the shieldmember 42, respectively.

As illustrated in FIG. 6, the holes 53A and 53B are provided at bothends of the cover 43 in the direction A, that is, the main scanningdirection, to engage the protrusions 52A and 52B depicted in FIG. 8.

As illustrated in FIG. 9, the hole 53A is a reference round hole and thehole 53B is an elongate hole elongating in the direction A, that is, themain scanning direction. Therefore, when the protrusions 52A and 52Bdepicted in FIG. 8 engage the holes 53A and 53B, respectively, the holes53A and 53B can absorb dimensional deviation between the shield member42 depicted in FIG. 8 and the cover 43.

The elongate hole 53B elongating in the direction A, that is, the mainscanning direction, can prevent the LED board 45 depicted in FIG. 3 fromtilting in the direction B, that is, the sub-scanning direction.

As illustrated in FIG. 3, the cover 43 prevents or reduces externallight entering the optical scanning unit 40 from an outside of theoptical scanning unit 40. The reflection member 47 provided on theopposed surface 43B of the cover 43 guides emission light emitted by theLED package 46 to the reflection member 49.

According to this example embodiment, the reflection members 47 to 49include a base material molded to have a reflection plane shapecorresponding to the opposed surface 43B of the cover 43 and the opposedsurface 42A of the shield member 42, and aluminum evaporated onto asurface of the base material.

Alternatively, the reflection members 47 to 49 may include a basematerial molded to have a reflection plane shape, and a reflectionsheet, such as an aluminum foil sheet attached to the base material. Yetalternatively, the reflection members 47 to 49 may include a reflectionsurface kneaded with a reflection material to coat the reflectionmembers 47 to 49. Yet alternatively, the reflection members 47 to 49 maybe plated with a reflection material.

According to this example embodiment, the protrusions 52A and 52Bdepicted in FIG. 8 engage the holes 53A and 53B depicted in FIG. 9,respectively, to position the shield member 42 relatively to the cover43. Therefore, the grooves 50 and 51 provided in the cover 43 and theshield member 42, respectively, to position the LED board 45 can beprovided in directions perpendicular to the exposure glass 7. Thus, theLED board 45 can be held vertically. Consequently, the LED package 46can emit light from the emission surface provided parallel to the LEDboard 45 in such a manner that the center axis of the light extends inthe horizontal direction.

The emission surface of the LED package 46 is oriented to extend thecenter axis of the emission light emitted by the LED package 46 in thehorizontal direction. Accordingly, the emission light emitted by the LEDpackage 46 travels substantially in the horizontal direction whilespreading in a reference angle.

Emission light emitted by the LED package 46 and reflected by thereflection member 48 provided on the shield member 42 irradiates theirradiation region W1 on an original document sheet P from a left sideof the irradiation region W1 in FIG. 3. Emission light reflected by thereflection member 47 provided on the cover 43 is further reflected bythe reflection member 49 provided on the shield member 42, andirradiates the irradiation region W1 on the original document sheet Pfrom a right side of the irradiation region W1 in FIG. 3. Emissionlight, which directly irradiates the reflection member 49 provided onthe shield member 42 from the LED package 46 and is reflected by thereflection member 49, also irradiates the irradiation region W1 on theoriginal document sheet P from the right side of the irradiation regionW1 in FIG. 3.

The irradiation region W1 is a given range on the exposure glass 7. Whenthe right side of the irradiation region W1 is defined as a front sidein the direction B, that is, the sub-scanning direction, and the leftside of the irradiation region W1 is defined as a rear side in thedirection B, that is, the sub-scanning direction, the reflection members47 to 49 cause light to irradiate the irradiation region W1substantially uniformly from the front and rear sides in the directionB, that is, the sub-scanning direction. Accordingly, a three-dimensionalimage, such as a cut-and-paste image, on an original document sheet Pdoes not shade the original document sheet P.

The cover 43 and the shield member 42 are bent to guide emission lightemitted by the LED package 46 toward the irradiation region W1 withuniform illuminance distribution in the direction B, that is, thesub-scanning direction.

In the optical scanning unit 40, the lighting device 56 is providedinside the housing 41, and includes the LED unit 44, the cover 43, andthe shield member 42. The LED unit 44 emits light. The cover 43 isprovided with the reflection member 47 for reflecting the emission lightemitted by the LED unit 44 toward the irradiation region W1 on anoriginal document sheet P. The shield member 42 is provided with thereflection members 48 and 49 for reflecting the emission light emittedby the LED unit 44 toward the irradiation region W1 on the originaldocument sheet P.

The shield member 42 is detachably attached to the housing 41, anddivides an inside of the housing 41 into the first space 57 in which theLED unit 44 is provided, and the second space 58 in which the readingdevice 54 is provided. The second space 58 is provided under the firstspace 57. In other words, the shield member 42 separates or shields thereading device 54 from the lighting device 56 so as to provide thesecond space 58, which contains the reading device 54, inside thehousing 41.

The opposed surface 42A of the shield member 42 forms a bottom portionof the lighting device 56. The shield member 42 separates or shields thesecond space 58 from the first space 57 so that light other thanreflection light reflected by an original document sheet P does notenter the second space 58. The shield member 42 covers a lower portionof the lighting device 56, and is attached to the housing 41 in such amanner that no gap is provided between the shield member 42 and thehousing 41.

The reflection member 47 is provided on the opposed surface 43B of thecover 43, which opposes the first space 57. The reflection members 48and 49 are provided on the opposed surface 42A of the shield member 42,which opposes the first space 57. Thus, the first space 57, which isseparated from the second space 58, is provided.

As illustrated in FIGS. 3, 7, and 8, the slit 59 is provided in theshield member 42, and extends in the direction A, that is, the mainscanning direction. The slit 59 is provided at a position far away fromthe LED unit 44 in a right side of the LED unit 44 in FIG. 3.

The slit 59 is provided between the reflection members 48 and 49, andguides reflection light reflected by an original document sheet P, forexample, reflection light reflected by an image on the original documentsheet P, from the first space 57 to the second space 58.

The slit 59 provides a top-to-bottom opening. A top of the opening isprovided at a position higher than a center of the LED package 46. Inother words, the slit 59 is provided closer to an original documentsheet P. Accordingly, the slit 59 suppresses or reduces emission lightemitted by the LED package 46 and entering from the first space 57 tothe second space 58. Consequently, the slit 59 guides reflection lightreflected by the original document sheet P into the second space 58.

A surface of the shield member 42 near the slit 59, on which thereflection members 48 and 49 are not provided, and an innercircumferential surface of the slit 59 in a vertical direction areprocessed by surface processing to provide a low reflectance orprocessed in black, so that a portion of the opposed surface 42A of theshield member 42, on which the reflection members 48 and 49 are notprovided, does not reflect light easily.

The reflection mirrors 60A to 60E, the image forming lens 61, and theCCD 63 are attached to the housing 41 in the second space 58. The CCD 63serves as an image pickup device. The reflection mirrors 60A to 60E, theimage forming lens 61, and the CCD 63 serve as the reading device 54.

When emission light emitted by the LED unit 44 irradiates theirradiation region W1 on an original document sheet P via the reflectionmembers 47 to 49, reflection light L reflected by the original documentsheet P in the irradiation region W1 in the main scanning direction isguided to the second space 58. For example, a light axis of thereflection light L is guided to the second space 58 via the slit 59provided in the shield member 42. Accordingly, the reflection mirrors60C, 60B, 60A, 60D, and 60E reflect the reflection light L in thisorder. Namely, the reflection mirrors 60A to 60E are attached to givenpositions on the housing 41 to guide the reflection light L to the imageforming lens 61.

The image forming lens 61 is attached to a bottom of the housing 41, andforms the reflection light L reflected by the reflection mirror 60E intoan image. The CCD 63 is attached to one side of the housing 41 in thedirection B, that is, the sub-scanning direction, at a position at whichthe image forming lens 61 forms the image. Thus, the CCD 63 reads anoriginal image on an original document sheet P. According to thisexample embodiment, the optical scanning unit 40 includes a plurality ofCCDs 63 corresponding to red, green, and blue, respectively, to read acolor image on an original document sheet P.

The CCD 63 is mounted on the SBU 64 attached to one side of the housing41 in the direction B, that is, the sub-scanning direction. In additionto the CCD 63, electronic parts, such as an IC (integrated circuit) chipand a chip condenser, are mounted on the SBU 64 to perform imageprocessing on an image read by the CCD 63 to generate image data to besent to the exposure device 31 depicted in FIG. 1.

Referring to FIGS. 10 to 13, the following describes a structure of thehousing 41 and a relation of the housing 41 to the shield member 42 andthe cover 43.

FIG. 10 is a perspective top view of the housing 41. As illustrated inFIG. 10, the housing 41 includes grooves 66.

FIG. 11 is an exploded, partially perspective view of the opticalscanning unit 40 when the housing 41, the shield member 42, and thecover 43 are disassembled from each other. As illustrated in FIG. 11,the housing 41 further includes a groove 70. The groove 70 includes abolt hole 70A.

FIG. 12 is an exploded, partially perspective view of the opticalscanning unit 40 when the housing 41 and the shield member 42 aredisassembled from the cover 43.

FIG. 13 is a partially perspective view of the optical scanning unit 40when the housing 41, the shield member 42, and the cover 43 areassembled. As illustrated in FIG. 13, the housing 41 further includes abolt 71.

As illustrated in FIG. 10, the grooves 66 are provided at both ends ofthe housing 41 in the direction A, that is, the main scanning direction,as a pair of grooves 66 serving as a first positioner. A line connectingan inner side of one of the grooves 66 to an inner side of another oneof the grooves 66 is parallel to the direction A, that is, the mainscanning direction. FIGS. 11 to 13 illustrate one of the grooves 66.

As illustrated in FIG. 8, the protrusions 61 are provided at both endsof the shield member 42 in the direction A, that is, the main scanningdirection, to serve as a second positioner. The protrusions 67 protrudehorizontally from both ends of the shield member 42 in the direction A,that is, the main scanning direction, to engage the grooves 66 depictedin FIG. 10, respectively.

When the shield member 42 is attached to the housing 41 depicted in FIG.10 by engaging the protrusions 67 with the grooves 66, the LED unit 44is positioned with respect to the reflection mirrors 60A to 60E, theimage forming lens 61, and the CCD 63 depicted in FIG. 3.

In the image forming apparatus 1 depicted in FIG. 3, emission lightemitted from the LED package 46 to the irradiation region W1 on anoriginal document sheet P includes red, green, and blue lines, each ofwhich has a width of several tens of micrometers.

Therefore, when reflection light L reflected by the original documentsheet P enters the CCD 63 via the reflection mirrors 60A to 60E and theimage forming lens 61 in a state in which the light axis of thereflection light L is shifted, a balance among amounts of lightcorresponding to red, green, and blue may fluctuate, and thereby the CCD63 may not read a bright image.

To address this, according to this example embodiment, the protrusions67 (depicted in FIG. 8), which are provided at both ends of the shieldmember 42 in the direction A, that is, the main scanning direction, toposition the LED unit 44 and the reflection members 47 to 49 withrespect to the reflection mirrors 60A to 60E, the image forming lens 61,and the CCD 63, engage the grooves 66 (depicted in FIG. 10) provided inthe housing 41. Therefore, simply attaching the shield member 42 to thehousing 41 can generate uniform illuminance distribution in thesub-scanning direction in the irradiation region W1 on an originaldocument sheet P to cause a position of a peak amount of light in theilluminance distribution to correspond to a center of a reading region,that is, a center of the CCD 63.

As illustrated in FIGS. 3 and 11, the grooves 66 and the protrusions 67are provided near the grooves 50 and 51 provided in the cover 43 and theshield member 42, respectively, to position the LED board 45. The upperend and the lower end of the LED board 45 engage the grooves 50 and 51,respectively. After the LED board 45 is attached to the cover 43 and theshield member 42, the protrusions 67 engage the grooves 66,respectively. Thus, when the cover 43 and the shield member 42 areattached to the housing 41, the LED board 45 is positioned in parallelto the direction A, that is, the main scanning direction.

The grooves 66 and the protrusions 67 provided near the grooves 50 and51 for positioning the LED board 45, respectively, can position the LEDboard 45 in a direction in which the center axis of emission lightemitted by the LED package 46 is substantially parallel to thehorizontal direction with improved precision.

As illustrated in FIG. 11, the groove 70 is provided in one side of thehousing 41 in the direction A, that is, the main scanning direction. Thebolt hole 70A is provided on a bottom of the groove 70.

As illustrated in FIG. 8, the bolt hole 72 is provided at one end of theshield member 42 in the direction A, that is, the main scanningdirection. A thread is formed on an inner circumferential surface of thebolt hole 72. When the shield member 42 is attached to the housing 41,the bolt hole 72 of the shield member 42 is aligned with the bolt hole70A of the housing 41 depicted in FIG. 11.

As illustrated in FIG. 13, when the bolt 71 is screwed into the bolthole 72 via the bolt hole 70A, the shield member 42 is fixed to thehousing 41. Depth of the groove 70 is substantially equal to height of ahead of the bolt 71, so that the head of the bolt 71 does not protrudefrom the side of the housing 41 in which the groove 70 is provided.

Referring to FIG. 3, the following describes a procedure for assemblingthe optical scanning unit 40.

After the upper end and the lower end of the LED board 45 engage thegroove 50 provided in the cover 43 and the groove 51 provided in theshield member 42, respectively, the protrusions 52A and 52B (depicted inFIG. 8) of the shield member 42 engage the holes 53A and 53B (depictedin FIG. 9) of the cover 43. Thus, positioning of the shield member 42with respect to the cover 43, that is, positioning of the reflectionmembers 48 and 49 with respect to the reflection member 47, is performedsimultaneously with positioning of the LED board 45 with respect to thereflection members 47 to 49.

For example, simply engaging the LED board 45 with the grooves 50 and 51can uniquely determine a position of the LED package 46 with respect tothe shield member 42 and the cover 43 to integrate the shield member 42with the cover 43, resulting in the lighting device 56 serving as aunit.

The hole 53B (depicted in FIG. 6) provided in the cover 43 is anelongate hole elongating in the direction A, that is, the main scanningdirection, preventing the LED board 45 from tilting in the direction B,that is, the sub-scanning direction.

Accordingly, in the LED unit 44, the LED board 45 is disposed betweenthe shield member 42 and the cover 43 in such a manner that the centeraxis of emission light emitted by the LED package 46 extendssubstantially in the horizontal direction.

Thereafter, the protrusions 67 (depicted in FIG. 8) provided at bothends of the shield member 42 in the direction A, that is, the mainscanning direction, engage the grooves 66 (depicted in FIG. 10) providedin the housing 41, respectively, to attach the shield member 42 to thehousing 41. Accordingly, the shield member 42 divides the inside of thehousing 41 into the first space 57 in which the lighting device 56 isprovided, and the second space 58 in which the reading device 54 isprovided. Simultaneously, the LED unit 44 and the reflection members 47to 49 are positioned with respect to the reflection mirrors 60A to 60E,the image forming lens 61, and the CCD 63, so as to generate uniformilluminance distribution in the direction B, that is, the sub-scanningdirection in the irradiation region W1 on an original document sheet Pto cause the position of the peak amount of light in the illuminancedistribution to correspond to the center of the CCD 63.

Thereafter, the bolt 71 (depicted in FIG. 13) is screwed into the bolthole 72 (depicted in FIG. 8) via the bolt hole 70A (depicted in FIG. 11)to fix the shield member 42 to the housing 41. Thus, the opticalscanning unit 40 is assembled.

In order to read an original image on an original document sheet P inthe image forming apparatus 1, the LED package 46 of the LED unit 44emits emission light to the irradiation region W1 on the originaldocument sheet P while the driver 40A (depicted in FIG. 1) moves theoptical scanning unit 40 in the direction B, that is, the sub-scanningdirection.

In the LED unit 44, the emission surface of the LED package 46 isoriented to extend the center axis of the emission light emitted by theLED package 46 in the horizontal direction. Accordingly, the emissionlight emitted by the LED package 46 travels substantially in thehorizontal direction while spreading in a reference angle.

Emission light emitted by the LED package 46 and reflected by thereflection member 48 provided on the shield member 42 irradiates theirradiation region W1 on an original document sheet P from the left sideof the irradiation region W1 in FIG. 3. Emission light reflected by thereflection member 47 provided on the cover 43 is further reflected bythe reflection member 49 provided on the shield member 42, andirradiates the irradiation region W1 on the original document sheet Pfrom the right side of the irradiation region W1 in FIG. 3. Emissionlight, which directly irradiates the reflection member 49 provided onthe shield member 42 from the LED package 46 and is reflected by thereflection member 49, also irradiates the irradiation region W1 on theoriginal document sheet P from the right side of the irradiation regionW1 in FIG. 3.

Accordingly, the position of the peak amount of light in the illuminancedistribution in the irradiation region W1 corresponds to the center ofthe reading region, that is, the center of the CCD 63. Namely, the LEDunit 44 irradiates the irradiation region W1 on the original documentsheet P with uniform illuminance distribution. The reflection mirrors60A to 60E guide reflection light reflected by the original documentsheet P and forming a reading light axis to the image forming lens 61.The image forming lens 61 forms the light into an image at the center ofthe CCD 63.

The position of the peak amount of light in the illuminance distributionin the irradiation region W1 corresponding to the center of the readingregion may not fluctuate the balance among amounts of lightcorresponding to red, green, and blue, and thereby the CCD 63 can read abright color image.

As described above, according to this example embodiment, the lightingdevice 56 includes the LED unit 44, the shield member 42 and the cover43 sandwiching the LED unit 44, and the reflection members 47 to 49. Thereflection member 47 is provided on the opposed surface 43B of the cover43. The reflection members 48 and 49 are provided on the opposed surface42A of the shield member 42. The reflection members 47 to 49 causeemission light emitted by the LED package 46 to irradiate theirradiation region W1 on an original document sheet P from the front andrear sides of the irradiation region W1 in the direction B, that is, thesub-scanning direction. The LED unit 44 is detachably attached to theshield member 42 and the cover 43. The groove 50 is provided in theopposed surface 43B of the cover 43 to position the reflection member 47with respect to the LED unit 44. Similarly, the groove 51 is provided inthe opposed surface 42A of the shield member 42 to position thereflection members 48 and 49 with respect to the LED unit 44.Accordingly, fluctuation in the illuminance distribution in theirradiation region W1 can be suppressed or reduced in the direction B,that is, the sub-scanning direction, maintaining a stable amount oflight supplied to the irradiation region W1.

The LED board 45 is detachably attached to the groove 50 provided in thecover 43, on which the reflection member 47 is provided, and the groove51 provided in the shield member 42, on which the reflection members 48and 49 are provided. In other words, the lighting device 56 can bedisassembled to clean or replace the reflection members 47 to 49 and theLED unit 44, and then assembled, providing improved efficiency ofmaintenance.

Further, the lighting device 56 includes the LED unit 44, the shieldmember 42, and the cover 43 independently provided from each other. TheLED board 45 engages the groove 50 provided in the cover 43 and thegroove 51 provided in the shield member 42, so that the cover 43 and theshield member 42 sandwich the LED unit 44 to assemble the lightingdevice 56. Therefore, the cover 43 and the shield member 42 can bemolded easily, improving productivity of the lighting device 56.

The cover 43 is detachably attached to the shield member 42, andemission light emitted by the LED unit 44 irradiates an originaldocument sheet P through the opening 43A provided between the cover 43and the shield member 42, resulting in the simple structure of thelighting device 56 and reduced manufacturing costs of the lightingdevice 56. A user can easily access the LED unit 44 and the reflectionmembers 47 to 49 by removing the cover 43 from the housing 41, resultingin easy maintenance of the lighting device 56.

As illustrated in FIG. 4, the LED unit 44 includes the plurality of LEDpackages 46 aligned substantially straight in the direction A, that is,the main scanning direction. As illustrated in FIG. 3, the LED packages46 can be positioned with respect to the reflection member 47 providedon the cover 43 and the reflection members 48 and 49 provided on theshield member 42 in such a manner that the LED packages 46 are arrangedparallel to the direction A, that is, the main scanning direction(depicted in FIG. 4). Accordingly, the LED unit 44 and the reflectionmembers 47 to 49 can be disposed properly with respect to theirradiation region W1. Consequently, fluctuation in the illuminancedistribution in the irradiation region W1 may be suppressed or reducedin the direction B, that is, the sub-scanning direction, maintaining astable amount of light supplied to the irradiation region W1.

The grooves 50 and 51 extend in the main scanning direction.Accordingly, the LED packages 46 are aligned substantially straight inthe main scanning direction with respect to the reflection members 47 to49. Thus, the LED unit 44 and the reflection members 47 to 49 aredisposed properly with respect to the irradiation region W1.Consequently, fluctuation in the illuminance distribution in thedirection B, that is, the sub-scanning direction, can be suppressed orreduced in the irradiation region W1 to maintain a stable amount oflight supplied to the irradiation region W1.

The LED board 45 engages the grooves 50 and 51 to cause the cover 43 andthe shield member 42 to sandwich the LED unit 44. Accordingly, the LEDunit 44 is positioned with respect to the reflection members 47 to 49easily.

The shield member 42 divides the inside of the housing 41 into the firstspace 57, in which the lighting device 56 is provided, and the secondspace 58, in which the reading device 54 is provided. The reflectionmembers 48 and 49 are provided on the upper surface of the shield member42 to cause emission light emitted by the LED unit 44 to irradiate theirradiation region W1 on an original document sheet P. The elongate slit59 extending in the main scanning direction guides reflection lightreflected by the original document sheet P from the first space 57 tothe second space 58. Thus, the shield member 42 optically shields thereading device 54 from the lighting device 56 while providing an opticalpath for guiding the reflection light reflected by the original documentsheet P to the reading device 54.

For example, the shield member 42 can prevent or reduce emission lightemitted by the LED unit 44 and entering the CCD 63 via the reflectionmirrors 60A to 60E and the image forming lens 61. Namely, the shieldmember 42 can prevent or reduce light (e.g., flare light), other thanthe reflection light reflected by the original document sheet P,entering the reading device 54.

Particularly, when the reading device 54 includes at least one of thereflection mirrors 60A to 60E, flare light may easily generate accordingto arrangement of the reflection mirrors 60A to 60E. Further, when abarrel lens for reduction imaging is used as an image forming lensrather than a lens for same magnification imaging, such as Selfoc® LensArray used for a same magnification sensor, flare light may enter theCCD 63 easily. To address this, according to this example embodiment,the shield member 42 can shield light other than image forming light,that is, light for forming an image in the CCD 63, preventing orreducing flare light effectively.

As illustrated in FIG. 8, the protrusions 67 are provided at both endsof the shield member 42, on which the reflection members 48 and 49 areprovided, in the direction A, that is, the main scanning direction. Theprotrusions 67 engage the grooves 66 of the housing 41 (depicted in FIG.10) to position the lighting device 56 (depicted in FIG. 3) with respectto the reading device 54 (depicted in FIG. 3). Accordingly, a simpleoperation of attaching the shield member 42 to the housing 41 cangenerate uniform illuminance distribution in the sub-scanning directionin the irradiation region W1 to cause the position of the peak amount oflight in the illuminance distribution to correspond to the center of theCCD 63 (depicted in FIG. 3). Consequently, the CCD 63 can read a brightimage.

The shield member 42 is detachably attached to the housing 41, so that auser can access the reading device 54 easily to perform maintenance onthe reading device 54.

The opposed surface 42A of the shield member 42 forms the bottom portionof the lighting device 56, and the protrusions 67 for engaging thegrooves 66 of the housing 41, respectively, are provided at both ends ofthe shield member 42 in the direction A, that is, the main scanningdirection, so as to position the lighting device 56 with respect to thereading device 54 while preventing the LED unit 44 (depicted in FIG. 3)from tilting in the sub-scanning direction. Thus, a simple operation ofattaching the shield member 42 to the housing 41 can cause the positionof the peak amount of light in the illuminance distribution in theirradiation region W1 to correspond to the center of the CCD 63.Consequently, the CCD 63 can read a bright image.

According to the above-described example embodiment, the shield member42 is fixed to the housing 41 by the bolt 71 depicted in FIG. 13.Alternatively, the shield member 42 may be attached to the housing 41via an engaging member.

Referring to FIGS. 14 and 15, the following describes an opticalscanning unit 40X including such engaging member. FIG. 14 is aperspective top view of a cover 43X included in the optical scanningunit 40X. As illustrated in FIG. 14, the cover 43X includes an engagingmember 68. The engaging member 68 includes an engaging hole 68A. FIG. 15is a partially perspective view of the optical scanning unit 40X. Asillustrated in FIG. 15, the optical scanning unit 40X includes a shieldmember 42X. The shield member 42X includes a protrusion 69.

As illustrated in FIG. 14, the engaging members 68 are provided at bothends of the cover 43X serving as a first sandwiching member in thedirection A, that is, the main scanning direction. The engaging hole 68Ais provided in the engaging member 68. As illustrated in FIG. 15, theprotrusions 69 are provided at both ends of the shield member 42Xserving as a second sandwiching member in the direction A, that is, themain scanning direction. When the protrusions 69 engage the engagingholes 68A of the engaging members 68, respectively, the cover 43X isattached to the shield member 42X. The shield member 42X is attached tothe housing 41 by the bolt 71. Thus, the cover 43X and the shield member42X are attached to the housing 41.

Accordingly, the groove 70 and the bolt hole 72 (depicted in FIG. 8) maynot be needed to attach the shield member 42X to the housing 41. Namely,when the cover 43X is fixed to the housing 41 by the engaging member 68and the protrusion 69 engaging the engaging member 68, the shield member42X may be fixed to the housing 41 by the cover 43X.

Alternatively, a snap-fit may fix the shield member 42 and the cover 43to the housing 41 depicted in FIG. 3. Yet alternatively, after the cover43 is pushed into the shield member 42, the shield member 42 may bepushed into the housing 41. Yet alternatively, after the cover 43 isattached to the shield member 42, the shield member 42 may be fixed tothe housing 41 by a pin, or the shield member 42 may be hooked on thehousing 41.

According to the above-described example embodiments, the shield member42 divides the inside of the housing 41 into the first space 57 and thesecond space 58. Alternatively, the shield member 42 may be provided onan upper open end of the housing 41. For example, the shield member 42may serve as a lid for providing a space, in which the reading device 54is provided, inside the housing 41.

Referring to FIG. 16, the following describes an image forming apparatus1Y according to another example embodiment. FIG. 16 is a schematic viewof the image forming apparatus 1Y. The image forming apparatus 1Yincludes an optical scanning unit 40Y. The optical scanning unit 40Yincludes a reading device 54Y instead of the reading device 54 depictedin FIG. 3. The optical scanning unit 40Y further includes a reflectionmirror 83. The other elements of the image forming apparatus 1Y areequivalent to the elements of the image forming apparatus 1 depicted inFIG. 3. As illustrated in FIG. 16, the reading device 54Y includes afirst moving body 81, a housing 82, reflection mirrors 84 and 85, asecond moving body 86, an image forming lens 87, and/or a CCD(charge-coupled device) 88.

In the image reader 4 (depicted in FIG. 1) of the image formingapparatus 1Y, the optical scanning unit 40Y is provided inside thehousing 4A. The first moving body 81 moves in the direction B, that is,the sub-scanning direction, at a constant speed. The second moving body86 also moves in the direction B, that is, the sub-scanning direction,at a half speed of the first moving body 81. The image forming lens 87and the CCD 88 are fixed to the housing 4A.

In the first moving body 81, the lighting device 56, which is identicalto the lighting device 56 provided in the image forming apparatus 1depicted in FIG. 3, is detachably attached to the housing 82. The shieldmember 42 divides an inside of the housing 82 into the first space 57,in which the LED unit 44 is provided, and the second space 58, in whichthe reflection mirror 83 is provided. The second space 58 is providedunder the first space 57. In other words, the shield member 42 separatesthe lighting device 56 from the reflection mirror 83 in such a mannerthat the second space 58 containing the reflection mirror 83 is providedinside the housing 82.

Reflection light reflected by an original document sheet P is guidedfrom the first space 57 to the second space 58 through the slit 59, andis reflected by the reflection mirror 83. The reflection mirrors 84 and85 are provided in the second moving body 86, and reflect the lightreflected by the reflection mirror 83 toward the image forming lens 87.

The image forming lens 87 forms the light reflected by the reflectionmirror 85 into an image in the CCD 88 serving as an image pickup device.The CCD 88 is disposed at a position at which the light travelingthrough the image forming lens 87 forms an image, and reads the image.The reflection mirrors 84 and 85, the image forming lens 87, and the CCD88 serve as the reading device 54Y.

According to this example embodiment, the shield member 42 divides theinside of the housing 82 into the first space 57, in which the LED unit44 is provided, and the second space 58, in which the reflection mirror83 is provided. The slit 59 provided in the shield member 42 guidesreflection light reflected by an original document sheet P from thefirst space 57 to the second space 58. Thus, the shield member 42provides an optical path for guiding the reflection light reflected bythe original document sheet P to the reflection mirror 83, and opticallyshields the reflection mirror 83 from the lighting device 56.

Accordingly, the shield member 42 can prevent or reduce emission lightentering from the LED unit 44 to the reflection mirror 83. In otherwords, the shield member 42 can prevent or reduce emission light (e.g.,flare light), other than the reflection light reflected by the originaldocument sheet P, entering the reflection mirror 83. Consequently, theCCD 88 can read a bright image.

According to this example embodiment, the shield member 42 divides theinside of the housing 82 into the first space 57 and the second space58. Alternatively, the shield member 42 may be provided on an upper openend of the housing 82. For example, the shield member 42 may serve as alid for providing a space, in which the reflection mirror 83 isprovided, inside the housing 82.

According to the above-described example embodiments, a lighting device(e.g., the lighting device 56 depicted in FIGS. 3 and 16), a readingdevice (e.g., the reading device 54 depicted in FIG. 3 or the readingdevice 54Y depicted in FIG. 16), and an image forming apparatus (e.g.,the image forming apparatus 1 depicted in FIG. 3 or the image formingapparatus 1Y depicted in FIG. 16) can suppress or reduce fluctuation inilluminance distribution in the sub-scanning direction in an irradiationregion (e.g., the irradiation region W1 depicted in FIG. 3), maintaininga stable amount of light supplied to the irradiation region whileproviding improved efficiency of maintenance of the lighting device. Theabove-described example embodiments can be applied to a lighting devicefor emitting light to an original document sheet, a reading device usedin a copier, a facsimile machine, an image scanner, or the likeincluding the lighting device, an image forming apparatus including thereading device, or the like.

For example, the lighting device includes a light source (e.g., the LEDunit 44 depicted in FIG. 3), a first sandwiching member (e.g., the cover43 depicted in FIG. 3 or the cover 43X depicted in FIG. 15), a secondsandwiching member (e.g., the shield member 42 depicted in FIG. 3 or theshield member 42X depicted in FIG. 15), a reflection member (e.g., thereflection members 47 to 49 depicted in FIG. 3), and/or a positioningmember (e.g., the grooves 50 and 51 depicted in FIG. 3). The firstsandwiching member and the second sandwiching member sandwich the lightsource. The reflection member is provided on a first opposed surface(e.g., the opposed surface 43B depicted in FIG. 3) of the firstsandwiching member and a second opposed surface (e.g., the opposedsurface 42A depicted in FIG. 3) of the second sandwiching memberopposing the first opposed surface. The reflection member reflectsemission light emitted by the light source toward an irradiation region(e.g., the irradiation region W1 depicted in FIG. 3) on an originaldocument sheet (e.g., the original document sheet P depicted in FIG. 3).

The light source is detachably attached to the first sandwiching memberand the second sandwiching member. The positioning member is provided inthe first opposed surface of the first sandwiching member and the secondopposed surface of the second sandwiching member to position the lightsource with respect to the reflection member.

Alternatively, the light source may include a board (e.g., the LED board45 depicted in FIG. 3) mounting a plurality of light emitting elements(e.g., the LED packages 46 depicted in FIG. 4) aligned substantiallystraight in the main scanning direction. The first sandwiching memberand the second sandwiching member may sandwich the board of the lightsource. The lighting device may include, instead of the positioningmember, a concave member (e.g., the grooves 50 and 51) provided in thefirst opposed surface of the first sandwiching member and the secondopposed surface of the second sandwiching member to engage the board ofthe light source.

With the above-described structure, the reflection member reflectsemission light emitted by the light source toward the irradiation regionon the original document sheet. The light source is detachably attachedto the first sandwiching member and the second sandwiching member. Thepositioning member is provided in the first opposed surface of the firstsandwiching member and the second opposed surface of the secondsandwiching member to position the light source with respect to thereflection member. Accordingly, fluctuation in illuminance distributionin the irradiation region can be suppressed or reduced in thesub-scanning direction, maintaining a stable amount of light supplied tothe irradiation region.

The light source is detachably attached to the positioning memberprovided in the first sandwiching member and the second sandwichingmember on which the reflection member is provided. Accordingly, thelighting device is disassembled and assembled to clean or replace thereflection member and the light source, providing improved efficiency ofmaintenance.

Further, the lighting device includes the light source, the firstsandwiching member, and the second sandwiching member independentlyprovided from each other. The light source is positioned with respect tothe first sandwiching member and the second sandwiching member in such amanner that the first sandwiching member and the second sandwichingmember sandwich the light source, so as to assemble the lighting device.Accordingly, the first sandwiching member and the second sandwichingmember can be molded easily, improving productivity of the lightingdevice.

The light source includes the plurality of light emitting elementsaligned substantially straight in the main scanning direction.Accordingly, the plurality of light emitting elements is positioned withrespect to the reflection member provided on the first sandwichingmember and the second sandwiching member in such a manner that theplurality of light emitting elements is parallel to the main scanningdirection. Thus, the light source and the reflection member can beprovided at a proper position with respect to the irradiation region.Consequently, fluctuation in the illuminance distribution in theirradiation region can be suppressed or reduced in the sub-scanningdirection, maintaining a stable amount of light supplied to theirradiation region.

In the lighting device, the first sandwiching member is detachablyattached to the second sandwiching member. An opening (e.g., the opening43A), through which emission light emitted by the light source passes toirradiate the original document sheet, is provided between the firstsandwiching member and the second sandwiching member. The firstsandwiching member serves as a cover for shielding the light source froman outside of the lighting device.

Thus, the lighting device has a simple structure which can reducemanufacturing costs of the lighting device. A user can remove the coverfrom a housing of the lighting device to access the light source and thereflection member to perform maintenance of the lighting device easily.

The positioning member extends in the main scanning direction, andserves as grooves for engaging the light source.

Thus, the light source is aligned substantially straight with respect tothe reflection member in the main scanning direction. Accordingly, thelight source and the reflection member can be provided at a properposition with respect to the irradiation region. Consequently,fluctuation in the illuminance distribution in the irradiation regioncan be suppressed or reduced in the sub-scanning direction, maintaininga stable amount of light supplied to the irradiation region.

Further, the light source engages the grooves to cause the firstsandwiching member and the second sandwiching member to sandwich thelight source, so as to position the light source with respect to thereflection member, improving efficiency in positioning the light source.

An optical scanning unit (e.g., the optical scanning unit 40 depicted inFIG. 3, the optical scanning unit 40X depicted in FIG. 15, or theoptical scanning unit 40Y depicted in FIG. 16) includes the lightingdevice, the reading device, and/or a housing (e.g., the housing 41depicted in FIG. 3). The lighting device is detachably attached to thehousing. The reading device is provided inside the housing, and readsreflection light reflected by the original document sheet. The housinghouses the reading device and is movable in the sub-scanning direction.The second sandwiching member separates the reading device from thelighting device to form a space for the reading device inside thehousing. An elongate slit (e.g., the slit 59 depicted in FIGS. 3, 15,and 16) is provided in the second sandwiching member in such a mannerthat the slit extends in the main scanning direction to guide reflectionlight reflected by the original document sheet to the space for thereading device.

Thus, the slit provides an optical path for guiding the reflection lightreflected by the original document sheet to the reading device tooptically shield the reading device from the lighting device.

In other words, the second sandwiching member prevents or reducesemission light, which is emitted by the light source, entering thereading device. Namely, the second sandwiching member prevents orreduces emission light (e.g., flare light), other than reflection lightreflected by the original document sheet, entering the reading device.Accordingly, the reading device can read a bright image.

The reading device includes a plurality of reflection mirrors (e.g., thereflection mirrors 60A to 60E depicted in FIG. 3 or the reflectionmirrors 84 and 85 depicted in FIG. 16), an image forming lens (e.g., theimage forming lens 61 depicted in FIG. 3 or the image forming lens 87depicted in FIG. 16), and/or an image pickup device (e.g., the CCD 63depicted in FIG. 3 or the CCD 88 depicted in FIG. 16).

The plurality of reflection mirrors reflects reflection light reflectedby the original document sheet and guided to the space for the readingdevice through the slit. The image forming lens forms the lightreflected by the reflection mirrors into an image. The image pickupdevice reads the image, and is provided at an image forming position atwhich the image forming lens forms the image.

Thus, an optical path for guiding the reflection light reflected by theoriginal document sheet to the reading device is provided to opticallyshield the reading device from the lighting device.

For example, the second sandwiching member, serving as a shield member,prevents or reduces emission light, which is emitted by the lightsource, entering the reflection mirrors, the image forming lens, and theimage pickup device. In other words, the second sandwiching memberprevents or reduces emission light, other than the reflection lightreflected by the original document sheet, entering the reading device.

The optical scanning unit may include a housing (e.g., the housing 82depicted in FIG. 16) movable in the sub-scanning direction. At least areflection mirror (e.g., the reflection mirror 83 depicted in FIG. 16)for reflecting reflection light reflected by an original document sheettoward a reading device (e.g., the reading device 54Y depicted in FIG.16) for reading the reflection light reflected by the original documentsheet is provided inside the housing. The second sandwiching memberseparates the reflection mirror from the lighting device to form a spacefor containing the reflection mirror inside the housing. The elongateslit extending in the main scanning direction to guide reflection lightreflected by the original document sheet to the space containing thereflection mirror is provided in the second sandwiching member.

Thus, the slit provides the optical path for guiding the reflectionlight reflected by the original document sheet to the reflection mirrorto optically shield the reflection mirror from the lighting device.

In other words, the second sandwiching member prevents or reducesemission light, which is emitted by the light source, entering thereflection mirror. Namely, the second sandwiching member prevents orreduces emission light (e.g., flare light), other than reflection lightreflected by the original document sheet, entering the reflectionmirror. Accordingly, the reading device can read a bright image.

An image reader (e.g., the image reader 4 depicted in FIG. 1) includesthe optical scanning unit and/or a driver (e.g., the driver 40A depictedin FIG. 1) for moving the lighting device in the sub-scanning direction.

The image reader includes the lighting device which provides properilluminance distribution for reading an image in the sub-scanningdirection with improved precision as well as improved efficiency ofmaintenance of the lighting device.

The image forming apparatus includes the image reader and/or an imageforming device (e.g., the image forming device 5 depicted in FIG. 1) forforming an image on a recording medium according to the light read bythe reading device, that is, image data obtained by reading an image onan original document sheet with the reading device.

The image forming apparatus includes the image reader including thelighting device which suppresses or reduces fluctuation in theilluminance distribution in the sub-scanning direction in theirradiation region to maintain a stable amount of light supplied to theirradiation region and improve efficiency of maintenance of the lightingdevice.

The present invention has been described above with reference tospecific example embodiments. Nonetheless, the present invention is notlimited to the details of example embodiments described above, butvarious modifications and improvements are possible without departingfrom the spirit and scope of the present invention. It is therefore tobe understood that within the scope of the associated claims, thepresent invention may be practiced otherwise than as specificallydescribed herein. For example, elements and/or features of differentillustrative example embodiments may be combined with each other and/orsubstituted for each other within the scope of the present invention.

1. A lighting device, comprising: a light source to emit light; a firstsandwiching member including a first opposed surface; a secondsandwiching member including a second opposed surface opposing the firstopposed surface of the first sandwiching member, the first sandwichingmember and the second sandwiching member sandwiching the light source insuch a manner that the light source is detachably attached to the firstsandwiching member and the second sandwiching member; at least onereflection member provided on each of the first opposed surface of thefirst sandwiching member and the second opposed surface of the secondsandwiching member to reflect the light emitted by the light sourcetoward an irradiation region on an original document sheet; and apositioning member provided in the first opposed surface of the firstsandwiching member and the second opposed surface of the secondsandwiching member to position the light source with respect to thereflection members.
 2. The lighting device according to claim 1, whereinthe light source comprises a plurality of light emitting elementsaligned substantially straight in a main scanning direction to emitlight and wherein the second opposed surface of the second sandwichingmember opposes the first opposed surface of the first sandwiching memberacross a gap through which the light emitted by the plurality of lightemitting elements and reflected by the at least one reflection member isguided toward the irradiation region on the original document sheet. 3.The lighting device according to claim 1, further comprising: an openingprovided between the first sandwiching member and the second sandwichingmember, through which the light emitted by the light source passes toirradiate the original document sheet, wherein the first sandwichingmember is detachably attached to the second sandwiching member, andcomprises a cover to shield the light source from an outside of thelighting device.
 4. The lighting device according to claim 1, whereinthe positioning member comprises grooves extending in a main scanningdirection to engage the light source.
 5. An optical scanning unitincluding the lighting device according to claim 1, the optical scanningunit further comprising: a reading device to read light reflected by theoriginal document sheet; and a housing that houses the reading deviceand is movable in a sub-scanning direction, to which the lighting deviceis detachably attached, wherein the second sandwiching member separatesthe reading device from the lighting device to form a space for thereading device inside the housing, and wherein the second sandwichingmember includes a slit extending in a main scanning direction to guidethe light reflected by the original document sheet to the space for thereading device.
 6. The optical scanning unit according to claim 5,wherein the reading device comprises: a plurality of reflection mirrorsto reflect the light reflected by the original document sheet and guidedto the space for the reading device through the slit; an image forminglens to form the light reflected by the plurality of reflection mirrorsinto an image; and an image pickup device to read the image, provided ata position at which the image forming lens forms the image.
 7. An imagereader including the optical scanning unit according to claim 5, theimage reader further comprising a driver to move the lighting device inthe sub-scanning direction.
 8. An image forming apparatus including theimage reader according to claim 7, the image forming apparatus furthercomprising an image forming device to form an image on a recordingmedium according to the light read by the reading device.
 9. An opticalscanning unit including the lighting device according to claim 1, theoptical scanning unit further comprising: a reading device to read lightreflected by the original document sheet; a reflection mirror to reflectthe light reflected by the original document sheet toward the readingdevice; and a housing movable in a sub-scanning direction, inside whichthe reflection mirror is provided, wherein the second sandwiching memberseparates the reflection mirror from the lighting device to form a spacefor the reflection mirror inside the housing, and wherein the secondsandwiching member includes a slit extending in a main scanningdirection to guide the light reflected by the original document sheet tothe space for the reflection mirror.
 10. A lighting device, comprising:a light source to emit light, comprising a board mounting a plurality oflight emitting elements aligned substantially straight in a mainscanning direction; a first sandwiching member including a first opposedsurface; a second sandwiching member including a second opposed surfaceopposing the first opposed surface of the first sandwiching member, thefirst sandwiching member and the second sandwiching member sandwichingthe board of the light source in such a manner that the light source isdetachably attached to the first sandwiching member and the secondsandwiching member; at least one reflection member provided on each ofthe first opposed surface of the first sandwiching member and the secondopposed surface of the second sandwiching member to reflect the lightemitted by the light source toward an irradiation region on an originaldocument sheet; and a concave member provided in the first opposedsurface of the first sandwiching member and the second opposed surfaceof the second sandwiching member to engage the board of the lightsource.
 11. The lighting device according to claim 10, furthercomprising: an opening provided between the first sandwiching member andthe second sandwiching member, through which the light emitted by thelight source passes to irradiate the original document sheet, whereinthe first sandwiching member is detachably attached to the secondsandwiching member, and comprises a cover to shield the light sourcefrom an outside of the lighting device.
 12. The lighting deviceaccording to claim 10, wherein the concave member comprises groovesextending in the main scanning direction to engage the light source. 13.An optical scanning unit including the lighting device according toclaim 10, the optical scanning unit further comprising: a reading deviceto read light reflected by the original document sheet; and a housingthat houses the reading device and is movable in a sub-scanningdirection, to which the lighting device is detachably attached, whereinthe second sandwiching member separates the reading device from thelighting device to form a space for the reading device inside thehousing, and wherein the second sandwiching member includes a slitextending in the main scanning direction to guide the light reflected bythe original document sheet to the space for the reading device.
 14. Theoptical scanning unit according to claim 13, wherein the reading devicecomprises: a plurality of reflection mirrors to reflect the lightreflected by the original document sheet and guided to the space for thereading device through the slit; an image forming lens to form the lightreflected by the plurality of reflection mirrors into an image; and animage pickup device to read the image, provided at a position at whichthe image forming lens forms the image.
 15. An image reader includingthe optical scanning unit according to claim 13, the image readerfurther comprising a driver to move the lighting device in thesub-scanning direction.
 16. An image forming apparatus including theimage reader according to claim 15, the image forming apparatus furthercomprising an image forming device to form an image on a recordingmedium according to the light read by the reading device.
 17. An opticalscanning unit including the lighting device according to claim 10, theoptical scanning unit further comprising: a reading device to read lightreflected by the original document sheet; a reflection mirror to reflectthe light reflected by the original document sheet toward the readingdevice; and a housing movable in a sub-scanning direction, inside whichthe reflection mirror is provided, wherein the second sandwiching memberseparates the reflection mirror from the lighting device to form a spacefor the reflection mirror inside the housing, and wherein the secondsandwiching member includes a slit extending in the main scanningdirection to guide the light reflected by the original document sheet tothe space for the reflection mirror.
 18. A lighting device, comprising:means for emitting light; first and second means for sandwiching themeans for emitting, the first means for sandwiching the means foremitting including a first opposed surface and the second means forsandwiching the means for emitting including a second opposed surfaceopposing the first opposed surface of the first means for sandwichingthe means for emitting, the means for emitting being detachably attachedto the first and second means for sandwiching the means for emitting; aplurality of means for reflecting the light emitted by the means foremitting toward an irradiation region on an original document sheet, atleast one of the plurality of means for reflecting provided on each ofthe first opposed surface of the first means for sandwiching and thesecond opposed surface of the second means for sandwiching; and meansfor positioning the means for emitting with respect to the means forreflecting, the means for positioning provided in the first opposedsurface of the first means for sandwiching and the second opposedsurface of the second means for sandwiching.
 19. An image readerincluding the lighting device according to claim
 18. 20. An imageforming apparatus including the image reader according to claim 19.